The effects of fuel type and cathode off-gas recirculation on combined heat and power generation of marine SOFC systems

An increasing demand in the marine industry to reduce emissions led to investigations into more efficient power conversion using fuels with sustainable production pathways. Solid Oxide Fuel Cells (SOFCs) are under consideration for long-range shipping, because of its high efficiency, low pollutant emissions, and fuel flexibility. SOFC systems also have great potential to cater for the heat demand in ships, but the heat integration is not often considered when assessing its feasibility. This study evaluates the electrical and heat efficiency of a 100 kW SOFC system for marine applications fuelled with methane, methanol, diesel, ammonia, or hydrogen. In addition, cathode off-gas recirculation (COGR) is investigated to tackle low oxygen utilisation and thus improve heat regeneration. The software Cycle Tempo is used to simulate the power plant, which uses a 1D model for the SOFCs. At nominal conditions , the highest net electrical efficiency (LHV) was found for methane (58.1%), followed by diesel (57.6%), and ammonia (55.1%). The highest heat efficiency was found for ammonia (27.4%), followed by hydrogen (25.6%). COGR resulted in similar electrical efficiencies, but increased the heat efficiency by 11.9% to 105.0% for the different fuels. The model was verified with a sensitivity analysis and validated by comparison with similar studies. It is concluded that COGR is a promising method to increase the heat efficiency of marine SOFC systems.

Automated summary

In response to the growing demand for emission reduction in the marine industry, research is being conducted on efficient power conversion using sustainable fuels. Solid Oxide Fuel Cells (SOFCs) are considered a viable option for long-range shipping due to their high efficiency, low pollutant emissions, and fuel flexibility. This study evaluates the electrical and heat efficiency of a 100 kW SOFC system for marine applications fueled with methane, methanol, diesel, ammonia, or hydrogen, and investigates the use of cathode off-gas recirculation (COGR) to improve heat regeneration. The results suggest that COGR is a promising method to increase the heat efficiency of marine SOFC systems.